1. Field of the Invention
The present invention relates to a holographic display device and method for generating a hologram using redundancy of 3D video, and more particularly, to a holographic display device for generating a computer generated hologram (CGH) in consideration of redundancy of 3D video and a method for generating a hologram using redundancy of 3D video.
2. Discussion of the Related Art
Generally, computer generated hologram (CGH) can be classified into a calculation method attributed to a ray tracing method, a calculation method using a look-up table (LUT), a fast fourier transform applied method and the like. And, the CGH can also be classified into a method of general hologram having a wide viewing angle and a method of sub-hologram having a limited viewing angle. The look-up table can also be used in calculating a sub-hologram, thereby considerably enhancing computing speed.
In generating a general hologram according to a related art, there is an enhanced result of 26 times faster computing speed using a parallel processing machine which is called CM2 in a thesis of M. Lucente. “interactive computation of holograms using a look-up table” (1993), which enabled a speed to be upgraded by using a look-up table algorithm and there is another enhanced result of about 70 times faster computing speed implemented in a system operable in a general PC using Matlab programming language in a thesis of Seung-Cheol Kim, “effective generation of digital holograms of three-dimensional objects using a novel look-up table method” (2008).
Even today, in case of calculating a CGH using such a fast parallel computing solution as a graphics processing unit (GPU), a study for real-time implementation of CGH calculation capacity using look-up tables has been globally conducted.
Regarding a CGH generation using a sub-hologram method, the amount of the basically used LUT becomes considerably less than that of a general hologram. In case of a general hologram, assuming that the general hologram has a resolution of 1920*1080 and that a sub-hologram forms an observation window for an observer in 2 meters, if an object point located 1 meter away from a hologram has an LUT of resolution corresponding to a size of the observation window, it is able to represent one identical object point.
An observation window is configured in the size of 6 to 12 mm, which is little bit bigger than that of a pupil of the eye of an ordinary man. If it is converted by pixel unit, when a pixel size is 156 μm, it is possible to configure an LUT to have about 76*76 resolution. Compared to a general hologram, a sub-hologram sets a limit on an eye scope in which an observer can see things. Yet, in case of using LUT, the sub-hologram has an advantage in configuring the LUT in size considerably smaller than that of the LUT used in a conventional general hologram. Utilizing this, it facilitated to configure a sub-hologram based real-time hologram display system. VISIO 20 prototype launched at SID in 2007 by SeeReal company was able to demonstrate a real-time hologram with limited hardware capability (GPU: NVIDIA 7900 GTX).
Naturally, if hardware is designed with high specifications, real-time holograms can be generated without using a display look-up table. However, the utilization of the look-up table for a solution capable of generating a real-time hologram with the configuration of low hardware specifications can be very effective.